1. Field of the Invention
The invention relates to neutralization of aldehydes for the purpose of complying with waste disposal requirements established by federal and state environmental protection agencies, in particular, with forming non-reversible neutralized aldehydes which are non-hazardous and do not revert back to toxic aldehydes.
2. Description of Related Art
Waste disposal of aldehydes has become increasingly more difficult over the years. Treatment of wastes containing a certain amount of aldehyde prior to placement of the waste into the environment is required by law. The extent of such treatment may vary depending upon the location of where the waste is generated and the stringency of the environmental standards in that area. For example, waste containing aldehyde may be classified as a hazardous waste in California under 22 CAL. CODE REGS., TIT. 22, § 66696. Formaldehyde also may be considered a hazardous waste on the federal level under 40 C.F.R. § 261.33(e) if it is a commercial chemical product (e.g., pure technical grade formaldehyde or formaldehyde is the sole active ingredient of the product that is to be disposed). Every state has an environmental regulation that is at least as stringent as this formaldehyde standard. State regulations also may be more stringent than this standard.
Additionally, facilities that discharge waste water to Publicly Owned Treatment Works (“POTW”) or directly into navigable waters may be required to meet standards that are established by a government agency. The standard may vary for each facility depending upon the quality of the receiving water and the concentration of aldehyde found in the waste water that is discharged into the environment by industry in that area.
Waste containing aldehyde may be generated by a variety of processes. For example, aldehydes such as glutaraldehyde and o-phthalaldehyde (“OPA”) are used in disinfecting medical devices or instruments. Waste containing aldehydes also may be generated by painting operations, stripping operations related to floors, or other manufacturing operations.
Typically, ammonia and sodium bisulfite (“SBS”) are used to treat many aldehydes. These compounds, however, have not proven to be effective at neutralizing OPA in accordance with environmental regulations.
A waste is classified as a hazardous waste in California if the waste being examined “has an acute aquatic 96-hour LC50 less than 500 milligrams per liter (mg/L) when measured in soft water (total hardness 40 to 48 milligrams per liter of calcium carbonate) with fathead minnows . . . . ” 22 CAL. CODE REGS., TIT. 22, § 66696. LC50 represents the concentration of a waste that is necessary to kill 50% of a particular animal exposed to a waste.
Note that a nonhazardous waste is generally considered by federal and state environmental agencies as a waste that does not satisfy the criteria set forth in defining a hazardous waste. Therefore, wastes generated in California that have a LC50>500 mg/L are nonhazardous wastes and wastes having LC50<500 mg/L are classified as hazardous. SBS, for example, in combination with OPA, produces a product that is generally considered hazardous under California environmental law as shown in Table 1 by LC50 being consistently below 500 mg/L. For this study, CIDEX® OPA (commercially available from Advanced Sterilization Products®, a Johnson & Johnson Company of Irvine, Calif.) was used to supply the OPA.
TABLE 1Neutralization Of OPA Using SBSOPA ContentLC50Sample Type(%)(mg/L)CommentsFresh CIDEX ® OPA at 0.3%0.301%31.1 mg/L1OPAFresh CIDEX ® OPA at 0.15%0.158%50.4 mg/L2OPAReuse CIDEX ® OPA at 0.3%0.295%31.1 mg/L3OPASBS/OPA = 4:1N/A68.3 mg/L4SBS/OPA = 2:1N/A46.3 mg/L51 Fresh CIDEX ® OPA at 0.3% OPA was prepared by diluting the fresh Cidex OPA solution with deionized water. 2 Fresh CIDEX ® OPA at 0.15% OPA was prepared by diluting the fresh Cidex OPA solution with deionized water to the level of 0.15% of OPA. 3 Reuse of CIDEX ® OPA at 0.3% OPA was prepared by diluting the simulated reuse CIDEX ® OPA (14 days) with deionized water. 4 SBS/OPA = 4:1, 10% SBS (10 mL) was combined with 100 mL of the fresh CIDEX ® OPA solution at 0.3% OPA (sample 1 above) at the SBS/OPA molar ratio of 4 to 1 for 30 minutes, and then the combined solution was used in the 22 CAL. CODE REGS., TIT. 22, § 66696 test for California. 5 SBS/OPA = 2:1, 10% SBS (5 mL) was combined with or 100 mL of the fresh CIDEX  ® OPA solution at 0.3% OPA (sample 1 above) at the SBS/OPA molar ratio of 2 to 1 for 30 minutes, and then the combined solution was used for the fish test in the 22 CAL. CODE REGS., TIT. 22, §  66696 test for California. 
In addition to lacking the ability to effectively neutralize OPA, ammonia and SBS are problematic since they may be harmful to the environment.
FIG. 1 shows that when OPA is combined with SBS at the molar ratio of SBS/OPA=4:0 for 30 minutes, OPA has been neutralized since the OPA concentration is nondetectable in a high performance liquid chromatography (HPLC) analysis method, which has detection limit for OPA at 10 ppm. However, the end product is still classified as a hazardous waste as shown in Table 1. Therefore, even though the aldehyde is neutralized completely by a neutralizer, the end product may still be a hazardous waste.
The purpose of this invention is to invent an effective, non-hazardous, convenient and inexpensive neutralizer for glutaraldehyde, o-phthalaldehyde (OPA) and/or other aldehydes. Glutaraldehyde and o-phthalaldehyde are the main chemicals used in industry and hospital for high-level disinfection. The glutaraldehyde or o-phthalaldehyde needs to be neutralized after use before disposal, however, at this point, there are only very limited neutralization methods available. Commonly assigned patent application U.S. Ser. No. 09/321,964, entitled “ALDEHYDE NEUTRALIZER” suggests using amino acids such as glycine as neutralizers. While use of glycine offers an inexpensive, fast and non-hazardous solution to aldehyde neutralization, there are, however, some problems with the amino acid neutralizer approach. One problem is that Schiff's base solutions formed between o-phthalaldehyde and glycine is black. In Japan, the general feeling is that they do not like black color; therefore, hospitals send their used solution to the waste treatment companies for disposal, which is expensive. Another approach to the problem of aldehyde neutralization is offered by commonly assigned and co-pending patent application U.S. Ser. No. 09/747,230 entitled “REDUCTIVE AMINATION FOR ALDEHYDE NEUTRALIZATION” which teaches the reaction of aldehydes with amino acid neutralizers followed by reduction of the resulting imines to form amino acids as final environmentally friendly products. This method is best carried out on solid supports and the solid waste is disposed after application. In another approach, commonly assigned and copending patent application U.S. Ser. No. 09/746,344, entitled, “DEVICE AND METHOD OF USE FOR ALDEHYDE REMOVAL”, discloses using polymeric amines as scavengers to remove aldehydes from waste solutions. Although this method removes both glutaraldehyde and o-phthalaldehyde from the used disinfectant solution, the solid waste still must be handled separately.
Thus different approaches to the challenge of aldehyde neutralization are still needed for various situations. This invention is intended to offer another approach relating to neutralization of aldehydes as hereinafter described.